美国国防部5月18日发表声明对中国进行指责，称美国侦察机此前在南海“国际空域”执行“例行巡航”，中国方面对其进行了“不安全”拦截。中国国防部对此回应称，美国媒体报道的中国军机在南海上空拦截美国侦察机可能涉及到美军用飞机对中国的抵近侦察。

2001年4月1日，美国EP-3侦察机在中国海南岛附近海域上空侦查，中国海军航空兵派出2架歼-8II战斗机进行监视和拦截，其中一架僚机在中国海南岛东南70海里（110公里）的中国专属经济区上空与美军飞机发生碰撞，中国战斗机坠毁，飞行员王伟牺牲。

美国EP-3侦察机

这一事件使作者立刻想起2001年4月同样在南海发生的中美撞机事件，那起事件最终导致一名中国飞行员牺牲以及中美外交关系的恶化。美国增兵亚太以及频繁开展“航行自由计划”行动导致的南海军事化，进一步增加了再次发生中美军机相撞事件的可能性。再一次发生恶性事件的危险性引发了作者的疑问，那就是现行国际法能否为相关当事方的行动提供行为准则？如果不能的话，中美是否有必要签署一项海上防意外事件协议以管控这些危险相遇？

考虑到1982年《联合国海洋法公约》（以下称《公约》）作为调整海洋用途的海洋宪章重要性，可以首先分析《公约》所能发挥的作用。根据1982年《联合国海洋法公约》，世界海洋被划分为具有不同法律地位和适用不同法律制度的管辖区域，这些法律制度合理规定了沿海国和使用国之间的权利与义务，可以作为判断不同区域内相关行动合法性的标准。因此，要想判断美军的侦察行为是否合法，确定军机相遇事件的地点起着至关重要的作用。

美方经常宣称拦截事件发生在南海上空的国际空域。事实上，“国际空域”这一术语并未出现在1982年《联合国海洋法公约》（以下称《公约》）之中。基于美国公开发表的官方声明以及美海军指挥官行动手册所代表的美国立场，美方将领空以外的空域，其中主要包括专属经济区以及公海上空的空域，称为所谓的“国际空域”。这是一种典型的与国际社会认识不一致的美国看法。按着国际社会通行的看法，对于每一具体海域及其上空是根据《公约》和一般国际法赋予的具体名称来命名的，比如用领海、专属经济区以及公海等名称，但不会用美国发明创造的“国际海域”或“国际空域”。

虽然美国没有加入《公约》，并习惯性地选择某些对其有利的条款作为习惯法的规定，但这不妨碍国际公认的构成国际习惯的《公约》条款对美国的适用。但是，上述与国际社会不一致的美国看法极易导致很多严重的法律适用冲突，特别是针对专属经济区及其上空法律地位的不同理解。基于国际社会根据《公约》达成的共识，专属经济区是由专门制度调整的自成一类的区域，沿海国和海域使用国在该区域内拥有相对平衡的权利和义务。但是，美国作为非《公约》当事国，坚持认为专属经济区内有关航行和飞越的自由与公海上的航行和飞越自由无论在质和量上都是相同的。因此，美国与国际社会对于《公约》的不同理解当然会导致海上行动对峙的出现。

另一个或许能够规范美国侦察活动的是国际法中关于军用飞机不期相遇的规则，很多源自于中美同为当事国的1944年《国际民用航空公约》（《芝加哥公约》），该公约专门有一个名为“空中规则” 的附件2，对如何处理拦截民用航空器问题推荐了相关标准和最佳做法。但是它不适用于包括军机在内的国家航空器。

或许也可以援引2014年《中美关于海空相遇安全行为准则谅解备忘录》作为一个调整规范，尽管该谅解备忘录并没有法律拘束力。但是，这也存在一个关于究竟谁有资格作为法官来判断上述相遇行动的合法性的问题。任何人都不充当对自己行为进行评判的法官。五角大楼“表扬”中国飞行员在过去几年中以“安全和专业的方式飞行”，其实美国或许应该花费更多的时间来审查美国飞行员自己在南海、波罗的海以及世界上任何一个海域是否以安全和专业的方式飞行。

最后，如果上述国际文件都不能发挥作用，中美之间签署一项防止海上意外事件的协议是否可行呢？作者对此选项并不乐观。海上防意外事件协议的最佳范例应当使1972年《美苏关于公海防意外事件的协议》。但是，这项1972年协议并没有防止1988年黑海撞船事件的发生，在那次事件中苏联用军舰将未经允许非法进入其领海的美国军舰撞了出去。即使在最近的四月份，美国国防部长还在抱怨俄罗斯飞机在波罗的海对美军飞机的拦截不安全和不专业。

那么中美双方如何才能防止类似事件发生呢？作者认为，最好的办法是找到问题的根源并从根源入手。非常清楚的是，无论在南海、波罗的海或其它外国专属经济区发生的军机相遇事件，都是美国不远万里飞行到别国家门口的专属经济区进行抵近侦察造成的，而这就是问题的根源。因此，最好的解决方法就是美国停止类似的抵近侦察行为。前车之鉴，后事之师。美国是时候审视自己的行为以免重蹈覆辙了。国际社会也是时候做出一个选择，即是维护在美国版国际法基础上建立的美国主导的霸权海洋秩序，还是遵从《联合国海洋法》框架下由国际社会共同制定的国际海洋秩序？

On May 18, 2016, the Pentagon released a statement accusing China of conducting “unsafe” interception of a US reconnaissance plane in “international airspace” over the South China Sea. China's Ministry of National Defense responded by stating that incident “is probably about the close-in reconnaissance by U.S. military aircraft against China.”

The collision in 2001 of a Chinese PLA Navy J-8 fighter jet and a US Navy EP-3 spy plane off China’s Hainan Island caused the death of Chinese pilot Wang Wei.

US Navy EP-3 spy plane

This incident immediately reminds me of the 2001 EP-3 collision incident between China and U.S., also in the South China Sea, which led to the death of one Chinese pilot and the deterioration of bilateral relations. The militarization of the South China Sea, accelerated by recent U.S. military build-up in the Asia-Pacific, as well as the U.S. Freedom of Navigation operations, increases the risk of yet another deadly collision incident. The danger of another such incident raises the question about whether the existing international law could serve as the rule of the road to regulate the conducts of relevant parties. If the answer is no, then does China and the U.S. need to negotiate an Incident at Sea (INCSEA) Agreement to curtail such dangerous encounters?

Let's look at the 1982 United Nations Convention on the Law of the Sea (UNCLOS). Under UNCLOS, the world's oceans are divided into various jurisdictional zones, where different legal regimes with balanced rights and duties between coastal and user states apply respectively. These legal regimes serve as a benchmark for deciding on the lawfulness of the conduct of relevant parties. Consequently, the location of the incident plays a key role in judging the lawfulness of the U.S. reconnaissance activities.

The U.S. has, as always, claimed that the most recent interception took place over the South China Sea in international airspace, a term which can be found nowhere in UNCLOS. Based on the American position, as reflected in its public statement and Navy Commander's Operational Handbook, the term “international space” refers to the airspace over the maritime areas beyond territorial waters, which may include airspace over both the EEZs and the high seas. This is a typical American-only understanding of the international law of the sea versus the shared international understanding. The broader international community purports to name each maritime area and its above airspace with its exact name as stipulated under UNCLOS, such as the territorial sea, the EEZ, the High Seas, etc.

The U.S. is not a party to UNCLOS but habitually chooses convenient articles of the convention to its advantage as reflecting “customary international law”. This U.S.-designed term leads to serious conflicts of understanding of law regarding the legal status of each maritime area and its above airspace, in particular that of the EEZ and its above airspace. While the international community aligned under the 1982 convention takes the EEZ as a particular maritime zone regulated under a specific legal regime with balanced rights and obligations between the user and coastal states, the U.S., not a UNCLOS signatory, insists that the freedom of navigation and overflights exercised within and beyond EEZs “must be qualitatively and quantitatively the same as the traditional high seas freedoms recognized by international law”. Consequently, this different understanding of law may well lead to operational confrontation at sea.

Another element that may have a bearing on the analysis of lawfulness of the U.S. reconnaissance activities is the rules of international law regarding un-alerted air encounters between military aircrafts. The 1944 Chicago Convention on International Civil Aviation, to which both China and U.S. are parties, has an Annex 2 entitled Rules of the Air, which recommends standards and best practices with regard to the interception of civilian aircrafts, but it does not apply to the interception of state aircrafts, military aircrafts included.

One may also cite the China-U.S. MOU on Air and Maritime Encounters as a benchmark. Notwithstanding the non-binding force of the nature of the MOU, this also raises the question of who would be the judge to decide on lawfulness of such an encounter. Either side should not be the judge for itself. While the Pentagon “praised” the Chinese pilot for “flying in a safe and professional manner” over the past years, the U.S. should spend more time to review whether the American pilots are flying in a safe and professional manner in the South China Sea, the Baltic Sea, or in any part of world.

Finally, if the aforementioned international instruments failed to serve the purpose, would it be necessary for China and the U.S to negotiate and sign an INCSEA agreement? This author is not optimistic about the role of a possible INCSEA agreement. The most notable example of an INCSEA agreement was the Agreement between the United States and the USSR on the Prevention of Incidents on and over the High Seas, signed in 1972. However, this 1972 INCSEA Agreement failed to prevent the 1988 Black Sea Bumping Incident, where two USSR warships bumped out two American warships that illegally entered the Soviet territorial waters without prior approval. Even last April, the US Defense Secretary was complaining about the “unsafe and unprofessional manner” by the Russian aircrafts against American aircrafts in the Baltic Sea.

Then what can be done to avoid such incident? The author is of the view that the best way is to find the root cause of the problem and deal with it therefrom. It is crystal-clear that it is the US military aircrafts that fly thousands of miles to the rim of Chinese EEZs, to the airspace near Russia boarders, and to other foreign EEZs, to conduct close-in reconnaissance, which is the root cause of the problem. Consequently, the key to solve the problem is to stop such close-in reconnaissance activities on part of the U.S.History repeats itself if its lessons were not learned, and now is the time for the U.S. to review its conduct so as not to repeat a past mistake in the same area. It is also the time for the international community to choose between a hegemonic ocean legal order based on American interpretation of international law and a world ocean legal order under UNCLOS.